The world of polymers has progressed rapidly to transform material science from wood and metals of the 19th Century to the use of thermoset polymers of the mid-20th Century to the use of thermoplastic polymers of later 20th Century.
Thermoplastic elastomers combine the benefits of elastomeric properties of thermoset polymers, such as vulcanized rubber, with the processing properties of thermoplastic polymers.
Different types of polymers can serve different purposes when combined into a single construction. For example, “two-part component” extrusion or molding has recently become popular to provide one type of rheology in one part of the component and a second type of rheology in a second part of the component. A specific use of two-part component thermoplastic compounds is insulating strips for vehicle doors. One part has a relatively rigid theological structure for securing the component to the door, with the second part being a relative flexible rheological structure to compress and seal the door to the vehicle.
Polyamide, also called nylon, is an excellent polymer for the relatively rigid rheological structure. But nylon is notorious for being difficult to adhere to other types of polymers, particularly thermoplastic elastomers that are useful for the relatively flexible theological structure of an insulation strip for an automobile door seal.